Over the last 10 years, dozens (hundreds?) of colleges and universities have added courses related to environmental and social sustainability. While we love many of them (and have contributed to more than a couple), one of the biggest game-changers has been the launch of Coursera.

We are a social entrepreneurship company that partners with the top universities in the world to offer courses online for anyone to take, for free. We envision a future where the top universities are educating not only thousands of students, but millions. Our technology enables the best professors to teach tens or hundreds of thousands of students.

Here are four great Coursera classes on sustainability topics that have caught our eye. Check them out, and go search Coursera for hundreds of other courses in business, economics, sustainability, and so much more.